In recent years intelligent driver assistance systems have attracted increasing attention in the automotive industry. One of such systems can be a user interface that tracks and recognizes a driver's hand gestures. A gesture-based user interface can improve the driver's safety in automobiles. It allows drivers to focus on driving while interacting with the various control systems in the car like, for examples, air-conditioning.
For implementing a short-range radar sensor for hand gesture sensing, it was further found that Frequency Modulated Continuous Wave (FMCW) radar with multiple receivers is very well suited. In this system, the transmitted signal is frequency-modulated by a periodic saw-wave function. The transmitted wave is reflected at a moving object like a moving hand and the received reflected wave is subject to a frequency shift (Doppler shift) and is also subject to a time delay. The relative motion of the object with respect to the radar causes the Doppler shift and the signal travelling to and from the object causes the time delay. The transmitted signal and the received signal are then mixed to produce a beat-signal which can be evaluated to yield the distance of the moving object.
An FMCW radar system may comprise several devices such as, for example, a radio frequency (RF) front-end device, a baseband device, an analog-to-digital converter (ADC) device, a micro-controller (MCU) device, and an application processor (AP) device. After converting the received analog signals by the analog-to-digital converter to digital data, a very high number of digital data have to be processed and shifted to a signal processing and detection device. The number of digital data to be processed and shifted depends mostly on the number of reception antennas of the radar system.